/*
 * eXist Open Source Native XML Database
 * Copyright (C) 2004-2009 The eXist Project
 * http://exist-db.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *  
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *  
 *  $Id$
 */
package org.exist.xquery.functions;

import java.text.Collator;

import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;

/**
 * Base class for functions accepting an optional collation argument. 
 * @author wolf
 */
public abstract class CollatingFunction extends Function {
    public final static String THIRD_REL_COLLATION_ARG_EXAMPLE = "The third argument $collation-uri is relative so you only need to " +
        "specify the last part of a valid full collation-uri, e.g. " + 
        "'?lang=sv-SE', " +
        "'lang=sv-SE;strength=primary;decomposition=standard' "+
        "or 'swedish'.";
	/**
	 * @param context
	 * @param signature
	 */
	public CollatingFunction(XQueryContext context, FunctionSignature signature) {
		super(context, signature);
	}

	protected Collator getCollator(Sequence contextSequence, Item contextItem, int arg) throws XPathException {
		if(getSignature().getArgumentCount() == arg) {
			String collationURI = getArgument(arg - 1).eval(contextSequence, contextItem).getStringValue();
			return context.getCollator(collationURI);
		} else
			return context.getDefaultCollator();
	}
}